The closures — both in Republican states — came despite a mountain of evidence suggesting they hamper children’s learning, social interactions and ability to develop natural immunity to common infections.

And there are fears that more disruption could be in store for students in the coming months — with many schools, in states like New York, New Jersey and Michigan, returning after the Labor Day weekend. Johnson-Abernathy-Graetz (JAB) high school in Montgomery, Alabama, which has 1,500 students in grades 9 through 12, made the decision to switch to virtual classes just four days into its new academic year after 15 teachers caught Covid. There was no data on how many students were infected.